1. Field of the Invention
The present invention relates generally to plastic article shaping processes. More particularly it relates to the forming of continuous or indefinite length material with crimping or crinkling of strands or filaments.
2. Prior Art Background
Textured multifilament yarn was initially produced according to a procedure comprising three separate stages, viz., spinning, drawtwisting or draw-winding, and texturing. In the interest of increased efficiency and economy, as well as improved product quality, semi-integrated processes such as spin-draw-winding and draw-texturing were later developed. In today's market--where speed, efficiency, economy, and product quality must all be significantly enhanced in order to maintain a competitive position--a fully integrated spin-draw-texturing process is virtually a requirement for most producers. The present invention is an improved spin-draw-texturing process.
3. Statement of Closest Known Prior Art
The closest prior art of which the inventors are aware is set forth below.
1. U.S. Pat. No. 3,975,484, Okada, et al., relates to a process comprising melt spinning non-circular cross section polyamide filaments, which are allowed to cool, treated with a substantially non-aqueous oil, passed around a feed roll having a peripheral speed of more than about 200 meters per minute, passed in contact with a heated body through a contact angle between about 80.degree. and about 160.degree. with the surface temperature of the heated body maintained in the range of about 170.degree.-250.degree. C. and with the radius of surface curvature in the range of about 15-75 mm. The filaments are thereby subjected to one-sided heating and drawing, passed around a heated draw roll having a peripheral speed of more than about 800 meters per minute and a surface temperature of less than about 220.degree. C., whereupon they are passed through a steam jet crimper which is supplied with steam at a temperature in the range of about 200.degree.-350.degree. C. This detailed spin-draw-texturing process differs from the improvement which is the present invention in a number of significant aspects, the most notable being that the reference does not comprehend pre-tensioning the lubricated melt spun filaments beyond the elastic limit thereof at room temperature, viz., between about 15.degree. and 25.degree. C. prior to the drawing thereof, and pre-heating the pre-tensioned filamentary polymeric material to a temperature between about 40.degree. and 70.degree. C. prior to the drawing thereof.
2. U.S. Pat. No. 4,096,226, Martin, et al., relates to an integrated process for the continuous spinning, drawing, and texturing of polyamide filaments, in which the following steps are effected in immediate succession:
(a) melt spinning filaments of polyamide polymers at temperatures between 260.degree. and 295.degree. C. at a spin-draw ratio of between 1:10 and 1:60;
(b) drawing the spun filaments on at least 2 forwarding elements, the initial element having a surface temperature between 50.degree. and 120.degree. C. and the final element having a surface temperature between 80.degree. and 350.degree. C., at a draw ratio such that the drawn filament, on leaving the drawing stage, has an extensibility of between 10 and 50 percent; and
(c) texturing the drawn filaments at a velocity of between 800 and 3,000 meters per minute by an air jet process wherein the overfeed in the texturing stage is from 10 to 50 percent, and the filament temperature, prior to texturing, is between 50.degree. and 180.degree. C. Not comprehended in this reference is the requirement in the present invention that the following cooperative combination of steps must be employed:
(a) Lubricating the filamentary polymeric material from the melt spinning step by applying thereto a lubricating composition comprising (1) a lubricant and (2) a solvent in an amount of from 0 to 20 percent by weight of the lubricating composition;
(b) Pre-tensioning the lubricated melt spun filamentary polymeric material beyond its elastic limit at room temperature, viz., between about 15.degree. and 25.degree. C. prior to the drawing thereof; followed by
(c) Pre-heating the pre-tensioned filamentary polymeric material to a temperature between about 40.degree. and 70.degree. C. prior to the drawing thereof.
3. U.S. Pat. No. 3,939,639, Ellegast, relates to a continuous process for the production of textured multifilament yarns from synthetic thermoplastic high molecular weight polymers by spin-draw-texturing, wherein the unstretched multifilament yarn is directed from the spinning phase to the draw-texturing phase through tubes made of metal, plastics, glass, or ceramics. Nowhere taught or suggested in this reference is the requirement in the present invention that the following cooperative combination of steps must be employed:
Pre-tensioning the lubricated melt spun filamentary polymeric material beyond its elastic limit at room temperature, viz., between about 15.degree. and 25.degree. C. prior to the drawing thereof; followed by
Pre-heating the pre-tensioned filamentary polymeric material to a temperature between about 40.degree. and 70.degree. C. prior to the drawing thereof.
4. U.S. Pat. No. 3,854,177, Breen, et al., relates to a process and apparatus for texturing continuous multifilament yarn at high speeds to increase the bulk thereof. A stream of hot compressible fluid is jetted to form a turbulent region, into which the filamentary yarn is passed. The filamentary yarn is removed from the fluid stream by means of a foraminous surface, whereupon it is cooled with fluid on the foraminous surface to set the crimp prior to the imposing of any substantial tension thereon. In FIG. 3; in Col. 3, lines 64-68; and in Col. 4, line 66 to Col. 5, line 11, reference is briefly made to an integrated spin-draw-texturing process. However, nowhere is it taught or suggested that the following cooperative combination of procedural steps, which is the improvement of the present invention, should be followed:
(a) Lubricating the filamentary polymeric material from the melt spinning step by applying thereto a lubricating composition comprising (1) a lubricant and
(2) solvent in an amount of from 0 to 20 percent by weight of the lubricating composition,
(b) Pre-tensioning the lubricated melt spun filamentary polymeric material beyond its elastic limit at room temperature, viz., between about 15.degree. and 25.degree. C. prior to the drawing thereof; followed by
(c) Pre-heating the pre-tensioned filamentary polymeric material to a temperature between about 40.degree. and 70.degree. C. prior to the drawing thereof.
5. U.S. Pat. No. 4,070,432, Tamaddon, discloses the procedural steps of lubrication, pretensioning, and forwarding on cold feed rolls, in a process for the production of a low shrinkage polyester. To be sure, one of skill in the art could not predict in advance that process parameters applicable in Tamaddon's polyester process would have any utility whatever in applicants' instant nylon 6 (polycaprolactam) process. Moreover, Tamaddon's purpose is the production of a high tenacity, low shrinkage industrial yarn, which is untextured. Consequently, one of skill in the art would not even look to Tamaddon to find a solution to a problem in respect of the production of textured multifilament polycaprolactam yarn. That is to say, there is no reason why one of skill in the art would combine Tamaddon with any known reference or other texturing conditions to result in a process like applicants' integrated process for the production of textured multifilament polycaprolactam yarn.
Furthermore, pre-tensioning as taught by Tamaddon means tensioning necessary to provide yarn stability on the succeeding rolls. (See Col. 2 line 54 ff. of the Tamaddon reference.) On the other hand, the present invention requires pre-tensioning beyond the elastic limit of the fiber, the inventors having discovered that pre-tensioning below the elastic limit was not adequate for the successful operation of their process.
6. Japanese Pat. No. 48-32616 discloses the processing of nylon 66 for the purpose of producing an untextured, high tenacity tire cord fiber. The process is characterized by a three-step drawing operation within specifically-defined temperature ranges. In sharp contradistinction thereto, the present invention is directed to an integrated process for the production of textured polycaprolactam multifilament yarn by the combination in immediate succession of the procedural steps of melt spinning, one-step drawing, and texturing. Because nylon 6 (polycaprolactam) and nylon 66 do not generally respond in the same fashion to the same process parameters, one of skill in the art would not be in a position to predict that conditions taught by the Japanese patent would find any applicability in applicants' process. Moreover, since the purpose of the Japanese patent is to produce untextured, high tenacity fiber, such as tire cord, one of skill in the art wold not event look to the Japanese patent for any process parameters to be combined with any known texturing conditions to result in a process like applicants'. If certain narrowly-defined parameters found in the Japanese patent could in fact be combined with texturing conditions known in the art or other texturing conditions, the results of such a combination would indeed be surprising.
Furthermore, it must be pointed out that applicants' invention requires a pretensioning of the lubricated melt spun nylon 6 filaments beyond the elastic limit thereof at a temperature between about 15.degree. and 25.degree. C. prior to the one-step drawing thereof. In contrast thereto, the spin-draw process for nylon 66 of the Japanese patent comprehends a first drawing step subsequent to oiling, the draw ratio being anywhere in the range 1.01 to 1.25X. This initial drawing step is followed by heating from 50.degree. to 120.degree. C., which is in turn followed by two additional zones of drawing. Accordingly, applicants' pretensioning beyond the elastic limit is not specifically pointed out in the broad, general teachings of the Japanese reference, and a multitude of undesirable conditions having no applicability whatever in applicants' process are also included therein.
7. Japanese Kokai No. 52-40620 is directed to a low-fault, high-strength nylon-6 yarn. Employing conditions taught in this reference, it has been found by applicants that completely unacceptable results are obtained, in sharp contrast to the highly beneficial results of applicants' process as defined in the present claims. In this regard, particular reference should be made to Example 5 and FIG. 2, infra.